Almost everyone has had the experience of trying to remember a word and feeling that it is just out of reach. You know what it means, and you are sure you know it, but it will not come. English speakers call this having a word "on the tip of the tongue." The American psychologist William James described the feeling as early as 1890.
In 1966, two researchers at Harvard University, Roger Brown and David McNeill, found a way to study the state in a laboratory. They read definitions of uncommon English words to a group of students and asked them to name each word. Sometimes a student knew the word at once, and sometimes not at all. But in many cases, the student felt sure the word was close.
These cases were the most revealing. Students in this state often knew a surprising amount about the missing word. More often than guessing would allow, they could name its first letter and say how many syllables it had. They also suggested other words that sounded similar to the target.
The study showed that the feeling is not an illusion. Instead of being completely lost, the word is partly available. The brain seems to store a word's meaning and its sound in ways that can be separated, so a person can reach the meaning while only part of the sound comes back.
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